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[193.116.118.220]) by smtp.gmail.com with ESMTPSA id v15sm18341830pfn.94.2019.01.21.22.46.30 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 21 Jan 2019 22:46:32 -0800 (PST) From: Nicholas Piggin To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH 2/4] powerpc/64s: system reset interrupt preserve HSRRs Date: Tue, 22 Jan 2019 16:46:16 +1000 Message-Id: <20190122064618.1510-3-npiggin@gmail.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20190122064618.1510-1-npiggin@gmail.com> References: <20190122064618.1510-1-npiggin@gmail.com> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Nicholas Piggin Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" The system reset interrupt may use HSRR registers (e.g., to call in to OPAL), but code that uses HSRR registers is not required to clear MSR[RI] by convention. Rather than introduce that requirement, have system reset interrupt save HSRRs before they might be used. Signed-off-by: Nicholas Piggin --- arch/powerpc/kernel/traps.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index b429b2264a1f..d54459152a2b 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -438,14 +438,32 @@ void hv_nmi_check_nonrecoverable(struct pt_regs *regs) void system_reset_exception(struct pt_regs *regs) { + unsigned long hsrr0, hsrr1; + bool hsrrs_saved = false; + bool nested = in_nmi(); + /* * Avoid crashes in case of nested NMI exceptions. Recoverability * is determined by RI and in_nmi */ - bool nested = in_nmi(); if (!nested) nmi_enter(); + /* + * System reset can interrupt a region where HSRRs are live and + * MSR[RI]=1, and it may clobber HSRRs itself (e.g., to call OPAL), + * so save them before doing anything. + * + * Machine checks should be okay to avoid this, as the real mode + * handler is careful to avoid HSRRs, and the virt code is not + * delivered as an NMI. + */ + if (cpu_has_feature(CPU_FTR_HVMODE)) { + hsrrs_saved = true; + hsrr0 = mfspr(SPRN_HSRR0); + hsrr1 = mfspr(SPRN_HSRR1); + } + hv_nmi_check_nonrecoverable(regs); __this_cpu_inc(irq_stat.sreset_irqs); @@ -495,6 +513,11 @@ void system_reset_exception(struct pt_regs *regs) if (!(regs->msr & MSR_RI)) nmi_panic(regs, "Unrecoverable System Reset"); + if (hsrrs_saved) { + mtspr(SPRN_HSRR0, hsrr0); + mtspr(SPRN_HSRR1, hsrr1); + } + if (!nested) nmi_exit(); -- 2.18.0